Modern farming practices often utilize towable agricultural tillage implements to prepare a seedbed providing optimal conditions for subsequent planting of seed in the seedbed, proper germination and growth of the seed, and conservation of the soil in and below the seedbed. Such implements are configured to provide a seedbed having a number of desirable conditions, including a uniform controlled depth, a flat and smooth floor at the bottom of the seedbed, and a relatively even surface finish.
To achieve these desired seedbed conditions, a number of factors must be taken into account in the design and set-up of the implement so that it will operate properly with a given towing vehicle operating at a desired speed. Some of these factors are interdependent, and to date have required iterative adjustments to get the implement set just right for producing the desired seedbed conditions.
Currently an operator must generally make some adjustments manually to the implement, using turnbuckles or manually operated hydraulic controls to get the implement properly set up for producing the desired seedbed conditions. The necessity for such manual adjustments result in undesirable delay and inconvenience for the operator. This is particularly the case where such adjustments must be partially made by person standing on the ground, rather than in the cab, or through the efforts of two people, one on the ground and one in the cab of the towing vehicle.
It is common for such towable agricultural tillage implements to have front and rear rows, or gangs, of tillage tools attached at front and rear ends of a frame of the towable implement. In such implements, adjustment of the depth of penetration of the front and rear rows of tillage tools is affected by the fore/aft level condition of the frame. For some types of implements and certain operating conditions, having the frame oriented substantially horizontally level with the ground under the implement results in production of optimal desired seedbed conditions.
In the past, there have been a number of approaches utilized for setting the fore/aft level of the frame generally horizontal to the ground under the implement, and for maintaining the frame as level as possible during operation of the implement. Such leveling was accomplished typically by manual adjustments made during initial set-up of the machine for operation at a given depth of penetration of the tillage tools. If tillage depth was increased or decreased, another iterative manual setup was often required to reset the fore/aft level of the frame.
Some prior and current systems utilize manually operable turnbuckles to adjust the levelness of the frame. These adjustments are typically cumbersome and time consuming. Other current systems utilize a manually operable hydraulic frame-leveling cylinder to adjust the fore/aft levelness of the frame. Systems using a manually operable frame-leveling cylinder offer considerable advantage in convenience and speed of adjustment. But even where such systems are designed such that the leveling cylinder can be controlled by the operator from the seat of the towing vehicle, making the required manual adjustments consumes more time than is desirable, and introduces unwanted opportunity for adjustment error.
Some prior approaches have attempted to automate the process of maintaining the frame in a substantially level attitude throughout a range of operating depths of the implement. Some of these approaches utilize a mechanical linkage arrangement that is adjusted manually during initial set-up of the implement to place the frame in a level condition. The linkage is configured such that, as the depth of the implement is adjusted through a limited range of operating depths, the linkage maintains the frame in a substantially level condition.
In another prior approach to automating fore/aft leveling of an implement frame, a mechanical leveling linkage includes one or more fore/aft leveling hydraulic cylinders that are plumbed into a hydraulic circuit used to set the tillage depth in such a manner that the fore/aft leveling cylinders automatically adjust the levelness of the frame to maintain the frame level as the tillage depth is changed, throughout a range of operating depths. Levelness is set by adjustments to the mechanical linkage during an initial set-up procedure. The fore/aft leveling cylinders then operate automatically within the leveling linkage to maintain the frame in a level position as the tillage depth is changed. This automatic operation of the leveling cylinders is achieved by selectively sizing the fluid capacity and flow characteristics of the fore/aft leveling cylinders, or by providing a flow divider/combiner, to maintain a fixed ratio of flow of hydraulic fluid to the fore/aft cylinders in proportion to the flow of hydraulic fluid in the tillage depth setting circuit, to thereby cause the fore/aft leveling cylinders to adjust the leveling linkage in a manner maintaining the frame in a level position. While this system provides considerable improvement over previous approaches it still requires an initial manual setup that is more cumbersome than is desirable, to properly complete initial adjustment of the leveling linkage. This approach also is limited to providing and maintaining a single, fixed adjustment of frame fore/aft level orientation that cannot be altered without repeating the set-up procedure. Such an approach also requires precise sizing of the hydraulic components for proper operation.
While all of the above approaches to setting and maintaining the fore/aft level of an implement frame have been used with varying degrees of success in the past, they are more cumbersome and time consuming than is desirable. Further improvements are desirable to simplify frame leveling adjustments through reducing manual adjustment, operator involvement, and allowing any adjustments related to leveling to be conveniently carried out while the implement is in the field without resorting to complex readjustments when depth of operation is changed.
In addition, experience has shown that maintaining a perfectly level frame orientation throughout the range of operating depths of a towable tillage implement may not always result in optimum seedbed preparation and operation of the implement. Experience has shown that sometimes optimum performance requires that the frame be tilted from a substantially level frame position. Optimal performance sometimes requires that the frame be tilted to a trim angle other than level. The degree of such tilting or trim angle that is desirable for achieving a desired seedbed condition may be depth dependent, such that, as depth of tillage changes throughout the operating depth range of the implement, the trim angle needs to change to a greater or lesser degree of optimal tilt as a function of the tillage depth.
For example, in some types of implements, such as disk-type vertical tillage implements, optimal performance is sometimes achieved when the frame is tilted, or trimmed, slightly toward the front or the rear rather than being substantially horizontally level. In such implements, interaction of the tilled soil discharged by the leading, (i.e. front), gangs of tillage tools with the trailing, (i.e. rear), gangs of tillage tools can result in a less than optimal seedbed surface having ridges and valleys that would hamper proper operation of seed planting equipment. It is known, in such instances, that making small adjustments to the fore/aft trim of the tillage implement can correct this condition and eliminate the ridges and valleys in the surface finish of the seedbed. The prior and current approaches described above to maintaining levelness of the frame generally do not lend themselves to conveniently making such trim adjustments.
The degree of tilt or trim required is typically related to the desired depth of the seedbed. Seedbed depth is consequently controlled by the depth of penetration of the front and rear tillage tools. With prior approaches, a desired smooth seedbed surface is often achieved only by an iterative process of: first, adjusting fore/aft trim to an essentially level position for uniform depth of penetration of the front and rear tillage tools, as measured just behind the blades of the front and rear tillage tools; second, adjusting the depth of penetration, verified again by measurement behind the blades of the front and rear tillage tools; and then, trimming the fore/aft level to tilt the frame to the front or rear to achieve the desired seedbed surface finish for the desired depth of penetration. Currently, some or all of these adjustment steps must be performed by the operator manually while standing on the ground with the implement, rather than totally from the cab or seat of the towing vehicle.
It is desirable, therefore, to provide an improved system, apparatus and method for adjusting the fore/aft level trim of the frame of a towed agricultural tillage implement. It is further desirable that such improvements include provisions for making these adjustments automatically, and without the necessity of the operator having to dismount from the towing vehicle to accomplish the required adjustments from the ground.